linux-kernel - [PATCH 1/7] drm/msm/a6xx: Fix unknown speedbin case

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Message-Id: <20230926-topic-a643-v1-1-7af6937ac0a3@linaro.org>
Date:   Tue, 26 Sep 2023 20:24:36 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Rob Clark <robdclark@...il.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        cros-qcom-dts-watchers@...omium.org,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Akhil P Oommen <quic_akhilpo@...cinc.com>
Cc:     Marijn Suijten <marijn.suijten@...ainline.org>,
        Luca Weiss <luca.weiss@...rphone.com>,
        Rob Clark <robdclark@...omium.org>,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org,
        Konrad Dybcio <konrad.dybcio@...aro.org>
Subject: [PATCH 1/7] drm/msm/a6xx: Fix unknown speedbin case

When opp-supported-hw is present under an OPP node, but no form of
opp_set_supported_hw() has been called, that OPP is ignored by the API
and marked as unsupported.

Before Commit c928a05e4415 ("drm/msm/adreno: Move speedbin mapping to
device table"), an unknown speedbin would result in marking all OPPs
as available, but it's better to avoid potentially overclocking the
silicon - the GMU will simply refuse to power up the chip.

Currently, the Adreno speedbin code does just that (AND returns an
invalid error, (int)UINT_MAX). Fix that by defaulting to speedbin 0
(which is conveniently always bound to fuseval == 0).

Fixes: c928a05e4415 ("drm/msm/adreno: Move speedbin mapping to device table")
Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
---
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index d4e85e24002f..522ca7fe6762 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -2237,7 +2237,7 @@ static int a6xx_set_supported_hw(struct device *dev, const struct adreno_info *i
 		DRM_DEV_ERROR(dev,
 			"missing support for speed-bin: %u. Some OPPs may not be supported by hardware\n",
 			speedbin);
-		return UINT_MAX;
+		supp_hw = BIT(0); /* Default */
 	}
 
 	ret = devm_pm_opp_set_supported_hw(dev, &supp_hw, 1);

-- 
2.42.0